American Citizen on Tue, 09 Jul 2024 01:25:45 +0200


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Re: Question: trying to locate other Diophantine triples from certain elliptic curves


To all:

I want to keep pursuing this question

We have an associated Elliptic Curve associated with a Diophantine Triple [a,b,c] where a*b+1, a*c+1 and b*c+1 are all squares.

(1)  E_triple(a,b,c)  = [0,(a*b+a*c+b*c),0,(a*b*c)*(a+b+c),(a*b*c)^2]

When I do run the GP Pari command for a specific set curve, say using the triple [5/4, 5/36, 32/9], I get the Curve as [0, 6625/1296, 0, 2225/729, 2500/6561]

There apparently are 4 isogenous curves associated with this curve in Weierstrass [0,0,0,a,b] format:

[-28511425/5038848, 149142030625/29386561536]

[-453599425/5038848, 9660698574625/29386561536]

[3360575/5038848, 464053326625/29386561536]

[-3935425/314928, -4396529375/459165024]

This is all mathematically fine and correct, but what I am looking for is the urst transformations such that I get a set of 4 curves, with [a_i, b_i, and c_i] a Diophantine triple.

Can we find the urst transformations to move these [0,0,0,a,b] curves to the (1) format  and have [a,b,c] be a Diophantine triple?

Randall